IBC Boiler-New Installation

[bigPipe09]

I Installed an IBC 15-150 for a customer about 3 months ago. The system is split into 3 injection loops; 1 for the garage in floor (2 zones) 1 for the basement in floor (2 zones) 1 for the domestic (80 gal storage tank with 24v aquastat)

As the homeowner was working in the garage and basement during construction, both in floor loops have been running perfectly for about 6 weeks.

The problem I came across is when I turned up the aquastat to heat the DHW tank, the boiler makes a god-awful vibrating noise. At first I thought maybe I had some air trapped in a loop, but I added an auto airvent and bled the loop again to ensure it was air-free. I also tested the fan by removing the power cable, which simulates the boiler blower running at full speed. The sound IS NOT coming from the blower. I am stumped on this one. When the boiler fires for the in floor call for heat, the firing rate is only about 70 MBH, when it fires for the DHW call, the firing rate is the max 150 MBH

Anyone have any insight?
Thanks

[plumberscrack]

Re: IBC Boiler-New Installation

Without seeing how each zone is piped, diagnosing won't be easy. I'm assuming you piped it Primary/Secondary right?

What was the noise heard and does it do it every time the DWH calls for heat? Loud screeching or hammer would lead me to believe not enough water is moving across the heat exchanger during the high fire for DHW. Confirm proper pump sizing and operation for both boiler trim and DHW.

Any zone valves in the system? You don't want pumps 'deadheading' into a zone valve while the boiler is firing.

Does it only make the noise when going from radiant heat to DHW?

Don't rule out the blower so soon. Any possible way the exhaust is being pulled back into the intake? Most boilers will shudder for 5 or 10 seconds when that happens.

Have you gotten any error codes on the display?

[bigPipe09]

Re: IBC Boiler-New Installation

[bigPipe09]

Re: IBC Boiler-New Installation

Without seeing how each zone is piped, diagnosing won't be easy. I'm assuming you piped it Primary/Secondary right?


Sorry about the size, this is an early pic obviously the piping was not complete but you get the idea. The top sec. loop is for garage, the right hand side sec. loop goes to DWH, the bottom sec.Bottom loop goes to basement in floor.


What was the noise heard and does it do it every time the DWH calls for heat? Loud screeching or hammer would lead me to believe not enough water is moving across the heat exchanger during the high fire for DHW. Confirm proper pump sizing and operation for both boiler trim and DHW.

Hard to describe, sounds more like a whining you would hear from a throttled urinal flush valve, if that makes any sense.


Any zone valves in the system? You don't want pumps 'deadheading' into a zone valve while the boiler is firing.

As you can see there are zone valves, but not on the domestic loops

Does it only make the noise when going from radiant heat to DHW?


Makes the noise any time the Aquastat fires the boiler, I have only fired it from cold, and at the max firing rate.

Don't rule out the blower so soon. Any possible way the exhaust is being pulled back into the intake? Most boilers will shudder for 5 or 10 seconds when that happens.


Its a lengthy noise, lasts the entirety of the firing cycle, also the intake is located about 40 feet from the exhaust(penetrates through the roof, intake is sidewall)


Have you gotten any error codes on the display?

At first it was displaying "No water flow", but this didnt happen after I bled all the air.

[plumberscrack]

Re: IBC Boiler-New Installation

I would drop the DHW pump and check it for debris.

Make sure the boiler trim pump is set to speed 3. Also, pop the check valve out of that pump. Double check the positing of that pump also. Control I don't think should be on the bottom. It's a Grundfos UPS-15-58 right? Not familiar enough with the IBC to know the flow rate though the boiler. Is that model Grundfos the right match or should it be the UPS-26-99?

Ball valve between the boiler and relief valve is a no-no here

[bigPipe09]

Re: IBC Boiler-New Installation

Thanks, for that, my boiler pump speed is currently set to 2, I will check the pump for debris. In hindsight that valve could have gone downstream of the relief valve, thats definitely the best practice, although the boiler would sense no flow and shut down before any harm could come of it.

[Lee H]

Re: IBC Boiler-New Installation

Growling you describe is typically the circulation through the boiler isn't sufficient for the firing rate, thus, temp rise (delta T) is too great. What you will hear is boiling or flashing inside the heat exchanger. You have one more speed to try but you may be required to increase circ size, I'm not able to tell from pic if anything else would be affecting circ rate through the boiler.

Fired at 150,000 with a delta t of 20 or more, you would need 12-15 GPM through the heat exchanger, I doubt you have that. Can you dial down input?

Couple things I notice:
1. usually the pump is on the supply outlet
2. highest temp zone, in this case the indirect water heater should be the first taps.

Also rather than take indirect off of primary if the unit is set up priority, it would have been better to pipe circ for DHW separately into S & R taps (parallel piping), thus circ for higher BTU domestic requirement could have been selected larger than primary/system pump.

[NHMaster3015]

Re: IBC Boiler-New Installation

Pull your primary circulator and replace it with a Wilo variable speed unit. Set the delta T for the max flo rate.

[bigPipe09]

Re: IBC Boiler-New Installation

Thanks for all the feedback, had a rep on the phone today and all he could suggest was a gummed up exchanger (due to construction dust & debris) and suggested a flush. At any rate I will see if there is a marked improvement when I turn the speed to "3", and that might tell me if I am on the right track.

[bigPipe09]

Re: IBC Boiler-New Installation

1. usually the pump is on the supply outlet
.

This is how the manufacturer suggests installing the pump. Also, IBC recommends 15-58, or wilostar 16f for this size primary loop and load. Not saying that is right, thats just how my rep sold it.

[Lee H]

Re: IBC Boiler-New Installation

This is how the manufacturer suggests installing the pump. Also, IBC recommends 15-58, or wilostar 16f for this size primary loop and load. Not saying that is right, thats just how my rep sold it.

I just looked at manual and it shows circ on top installed on supply outlet pipe, but in other places including sales lit it shows on return, they cant seem to make up their mind.

http://www.ibcboiler.com/PDF/15-150_45-225_manual.pdf

What they don't tell you in all the specs is the unit pressure drop or head. Important for sizing proper flow in unit. However looking at the pics of unit, the heat exchanger appears to be a fire-tube heat exchanger meaning the head should be low. Try that high speed.

[furnaceguy]

Re: IBC Boiler-New Installation

You may want to check your gas line sizing! If the boiler is vibrating it may be due to an undersized gas line resonating, similar to a lennox pulse style combustion. Also, I never install a wall hung boiler without a low loss header, it stops primary/secondary pumps from fighting each other, period.

[bigPipe09]

Re: IBC Boiler-New Installation

You may want to check your gas line sizing! If the boiler is vibrating it may be due to an undersized gas line resonating, similar to a lennox pulse style combustion. Also, I never install a wall hung boiler without a low loss header, it stops primary/secondary pumps from fighting each other, period.

I explored the low loss header option pretty deeply. Its definitely the best piping method. However it's not the most economical...



Gasline is 1 1/4" right to the boiler. It was just convenient because the main came in right over top of the boiler. I would've checked my gas line sizing before I piped it. Haha, I'm a better gasfitter than hydronic installer..for now

[bigPipe09]

Re: IBC Boiler-New Installation

Just wanted to update, flushed exchanger with Fernox commissioning solution and it solved the problem...I guess sometimes the answer is the most obvious one

[Scott K]

Re: IBC Boiler-New Installation

I know this is an old thread (year and a half old) - it came up in a search - but I'd like to point out that there is a valve between the pressure relief valve and the boiler. Essentially that boiler is now a potential bomb and this would NEVER pass an inspection where I live.